Gonococcal and Chlamydial infections are common forms of sexually transmitted diseases (STD). Current diagnostic procedures for these organisms are lengthy, laborious, and relatively insensitive and non-specific. A novel DNA-based diagnostic assay for the detection of Neisseria gonorrhoeae and Chlamydia trachomatis is described in this proposal. DNA probes specific for each of these organisms are currently available. DNA hybridization procedures using non-radioactive, biotinylated DNA probes were determined in our Phase I studies. Phase II of this project will focus on the development of rapid, user friendly non-growth assays for N. gonorrhoeae and C. trachomatis using biotin-based dot blot, in situ, or Sandwich type DNA detection systems. This approach has been successfully applied to the clinical diagnosis of herpes simplex viruses. Major emphasis will be placed on determining appropriate sample format, fixation, and hybridization conditions. In concurrent studies, the use of synthetic oligonucleotides will be developed as an alternate probe technology. While currently used procedures for probe preparation from recombinant sources will be adequate for the near term, the use of synthetic oligonucleotides may offer significant advantages with respect to cost, ease, and reproducibility for large scale production.